textproduct: Quad Cities

KEY MESSAGES

- There is an enhanced (level 3 out of 5) risk for severe weather late this evening/tonight. Damaging winds (some gusts over 70 mph) and a low risk for brief tornadoes will be the primary threats. - Multiple rounds of storms expected through this weekend and into early next week. Severe storms are possible each day through Tuesday, with low confidence on areal coverage Saturday and Sunday. - Widespread storms likely Sunday night through Monday, with increasingly warm and humid conditions.

SHORT TERM /THROUGH TONIGHT/

Issued at 231 PM CDT Fri May 15 2026

The "calm before the storm" conditions were seen early this afternoon with wall to wall sunshine across the CWA and temperatures in the upper 70s/low 80s. This is thanks in part to our very strong inversion at 900mb sampled by our 18z sounding, which has also kept our winds below 20kts today. A similar sounding was seen upstream at OAX, although much steeper mid-level lapse rates were seen there. METARs and RAP mesoanalysis showed the main parent low along the Manitoba/Ontario border with a boundary extending south to a surface low in central NE (near KODX), with a subtle warm front extending eastward towards Des Moines. Just north of this warm front, some agitated clouds were beginning to form in northwest IA close to Spencer.

Convective initiation should take place within the next 1-2 hours in northwest IA as MLCIN continues to erode. Storms will grow upscale through the evening tracking east towards eastern IA. A favorable environment for severe weather will be in place with deep layer shear values over 45 kts, steep mid- level lapse rates, and MLCAPE values over 1500 J/Kg. Latest CAMs all now suggest this activity becoming more of a QLCS, with damaging wind becoming the primary threat before they reach our northwest counties. Several bowing segments will be possible and with 0-3 km shear values around 30-35kts can't rule out some strong mesovorts/brief spin-ups tonight. A rather tight DCAPE gradient with values just over 1000 J/Kg and max theta-e differences in the 0-3km layer over 25C also support the potential for some 70+ mph gusts possible particularly west of the Quad Cities where the greater potential for mature/organized convection will exist and is highlighted by the SPC Enhanced Risk from SPC. Stay weather aware tonight!

This convection to push east southeast of the CWA after midnight, quickly diminishing in strength as the BL begins to stabilize. Overnight lows to drop into the upper 50s/lower 60s.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 231 PM CDT Fri May 15 2026

Saturday should be a day of increasing solar insolation fostering a rebound in highs into the 80s, with another nudge up in the humidity levels with widespread dew points in the 60s. Forcing is rather nebulous with some weak height rises depicted at 500 hPa. But, there is potential by mid to late PM with strong surface heating to weaken any CIN and trigger widely scattered storms. Low level shear is quite weak, but 30-40 kt of 0-6km shear and fat CAPE profiles would support a risk for severe storms perhaps with some supercellular characteristics capable of large hail and damaging winds. Coverage would appear to be spotty, and storms could continue beyond sunset. Blended guidance is quite high with precipitation chances evolving Saturday night into Sunday AM along/north of I-80 likely attendant to increasing WAA ahead of a lifting warm front as an upper trough undergoes amplification across the western CONUS. Seemingly the signal for the main LLJ core and advection appear to be aimed further west, and so my confidence on these higher PoPs is low. Nonetheless, we'll have a chance for showers and storms Saturday night into Sunday morning with the warm front lifting through the region. Thereafter, much of Sunday will be very summery as we are placed firmly within the warm sector with highs well into the 80s to possibly near 90 in a few spots and humid conditions. This could again trigger some widely scattered late day convection of which could be severe due to the abundant instability and at least modest shear.

The details in the forecast become murky late in the weekend through early next week, and severe storm potential will likely hinge some on previous days convective trends/evolution. That said, synoptically with the upper trough slowly shifting east placing the region in strengthening SW flow aloft shuttling embedded disturbances, and a surface cold front inching closer we have perhaps our best potential for more widespread storms and increased coverage of strong/severe storms late in the weekend through early next week. Potential to see another organized convective complex work through the area Sunday evening/night, and then how this evolves could play into the timing/location/threat for severe weather on Monday.

It looks like the cold front will shift through the region on Tuesday with one last chance for storms. Uncertainty still abounds with regards to any severe threat Tuesday, which is largely dependent upon the frontal timing. Cooler and more seasonable conditions look to settle in mid next week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1225 PM CDT Fri May 15 2026

VFR conditions to persist at least through 16.02z this evening at all terminals. Scattered showers and thunderstorms are expected to develop over western IA late this afternoon/evening tracking eastward across the state. As they push east, storms to congeal and form into a line or two with the potential for a few bowing segments bringing wind gusts over 50kts tonight, especially west of the MS RVR. Latest trends show a slightly slower progression of storms and have refined PROB30 groups to reflect this. Once storms form, further refinements/amendments may be done to better match trends. All activity to push east and southeast of the terminals after 16.10z. Some MVFR fog may develop at CID/DBQ in the wake of the storms as winds become light and variable.

Another storm system to bring additional storms just beyond this TAF cycle.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.